Effect of Diabetes Mellitus type 2 on Voice: A systematic review and Meta-analysis

Introduction: Diabetes Mellitus type 2 is a growing health concern that affects several systems in the body among which the phonatory apparatus. Voice may be affected in view of the high prevalence of myopathy and neuropathy in diseased subjects. The authors aim to answer the following question: Does type 2 diabetes have an effect on voice? Methods: The systematic review included search terms such as "speech, voice, larynx, glucose, diabetes, and hyperglycemia". The search strategy yielded 221 articles, only five of which satisfied the inclusion criteria. Articles were considered for inclusion using the PRISMA method. Analysis included 321 patients with type 2 diabetes mellitus and 171 controls. All studies included were case control studies except for one study which was an observational cohort. Six parameters were chosen as endpoints for the systematic review and meta-analysis: the presence/absence of voice complaints, fundamental frequency (fo), jitter, shimmer, noise to harmonic ratio (NHR) and maximum phonation time. Results: There was no significant difference in the prevalence of voice complaints (i.e., hoarseness) between diabetic patients and control groups. There was also no significant difference in any of the acoustic and aerodynamic measures between patients with type 2 diabetes and controls. These findings can be ascribed the high resilience of the laryngeal muscles to the adverse effect of systemic diseases. Conclusion: There is no consensus in the literature that the prevalence of voice symptoms in diabetic patients is significantly higher than that reported in healthy subjects.